* Retail sales drop 0.1 percent in Oct vs forecast of 0.2 pct gain
* Sales ex-autos climb 0.4 percent
OTTAWA, Dec 20 (Reuters) - Canadian retail sales unexpectedly fell by 0.1 percent in October from September as a downturn at car dealerships offset upbeat supermarket sales, Statistics Canada data showed on Friday.
Market analysts had forecast a 0.2 percent increase in monthly sales, according to the median forecast in a Reuters poll.
The weak reading followed three straight months of gains as four of the 11 retail subsectors declined. In volume terms, retail sales grew 0.2 percent in October.
Overall sales at motor vehicle and parts dealers fell 1.9 percent. New car sales slid 1.6 percent after a 4.6 percent surge in the previous month. Gasoline station sales fell 1.6 percent.
On the other hand, food and beverage stores registered a 1.7 percent jump in sales.
Total sales excluding the auto sector grew 0.4 percent.